Investigations of Pulse‐Plasma‐Polymer Coating on TiO2 Nanoparticles and Their Dispersion

An amorphous acrylic acid (AA) polymer coating was generated on TiO₂ nanoparticles through pulse radio frequency (RF) plasma polymerization. The AA plasma synthesis mechanism was studied by its optical emission spectrum. The chemical structures of AA–plasma‐polymer were carefully investigated by Fourier transform infrared spectroscopy (FTIR). The dispersion behaviors of AA‐coated and uncoated TiO₂ nanoparticles in glycol solution were characterized by ultraviolet absorbency and particle size distribution measurements. The results showed that the aggregation of TiO₂ nanoparticles in glycol solution was effectively lowered and the dispersion was improved a lot after AA–plasma‐polymer coating. The pulse plasma coating parameters played an important role in the dispersion enhancement of TiO₂ nanoparticles. By properly regulating the pulse discharge parameters, the system could gain the highest radical–monomer reactions rate, the most compatible functional groups on the nanoparticles, and the best dispersion in the background media.     

Preparation and Characterization of Polypyrrole/Ferrospinel Nanocomposite by W/O Microemulsion Pathway

A polypyrrole/ferrospinel(NiFe₂O₄) nanocomposite was prepared by the in situ chemical oxidizing of pyrrole in the presence of NiFe₂O₄ nanoparticles in water-in-oil (w/o) microemulsion. The structural, morphological, and magnetic properties of the as-prepared polypyrrole/NiFe₂O₄ nanocomposite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and magnetic measurements. XRD and FTIR revealed the presence of NiFe₂O₄ in the nanocomposite. SEM and TEM images illustrated that polypyrrole was coated on the NiFe₂O₄ surface. The electromagnetic parameters, such as conductivity, saturation magnetization, and coercivity of NiFe₂O₄ nanoparticles varied after coating with polypyrrole.     

Self-Assembled Microfibers of Simple Amphiphilic Molecules Through a Facile Precipitation Route

One-dimensional (1D) fiber structures of simple amphiphilic molecules were prepared through a facile precipitation route. The self-assembly process was studied by ultraviolet-visible absorption and Fourier transform infrared) spectroscopy, which indicated that hydrogen bonding interactions played a role in the1D growth along the axis of the fiber. The water content, self-assembling temperature, and concentration of 1,5-bis-(1-(pyridin-2-yl)ethylidene)thiocarbonohydrazide molecules in the solution had obvious effects on the size and morphology of the self-assembled products. The formation of1D superstructures is not only of a hot subject in the process of nanoscience but also opens a new venue for conveniently controlling self-assembled structures of similar organic molecules.     

Influence of Mixing Technique on Microstructure and Impact Properties of Isotactic Polypropylene/ Poly(Cis-Butadiene) Rubber Blends

Isotactic polypropylene/poly(cis-butadiene) rubber (iPP/PcBR vol%: 80/20) blends were prepared by melt mixing with various mixing rotation speeds. The effect of mixing technique on microstructure and impact property of blends was studied. Phase structure of the blends was analyzed by scanning electron microscopy (SEM). All of the blends had a heterogeneous morphology. The spherical particles attributed to the PcBR-rich phase were uniformly dispersed in the continuous iPP matrix. With increase of the mixing rotation speed, the dispersed phase particle's diameter distribution became broader and the average diameter of the separated particles increased. The spherulitic morphology of the blends was observed by small angle light scattering (SALS). Higher mixing rotation speed led to a more imperfect spherulitic morphology and smaller spherulites. Crystalline structure of the blends was measured by wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS). The introduction of 20 vol% PcBR induced the formation of iPPβ crystals. Higher rotation speed led to a decrease in microcrystal dimensions. However, the addition of PcBR and the increase of mixing rotation speed did not affect the interplanar distance. The long period values were the same within experimental error as PcBR was added or the mixing rotation speed quickened. The normalized relative degree of crystallinity of the blends slightly increased under lower rotation speeds (30 and 45 rpm) and decreased under higher rotation speeds. The notched Izod impact strength of the blends was enhanced as a result of the increase of mixing rotation speed.     

荧光染料掺杂的高效率、高亮度白色有机电致发光器件

制备了结构为 ITO/NPB（30 nm）/Rubrene（0.2 nm）/CBP：Bczvbi（8 nm,x%）/Bphen（30 nm）/Cs₂CO₃：Ag₂O（2 nm,20%）/Al（100 nm）的器件。研究了Bczvbi掺杂浓度（x=5,10,15）对白光器件性能的影响。综合利用发光层中主客体之间的能量转移和空穴阻挡层的空穴阻挡特性,得到了高效率、高亮度的白色有机电致发光器件。当Bczvbi的掺杂质量分数为10%时,器件的效率和亮度都为最大。驱动电压为7 V时,最大电流效率为4.61 cd/A;驱动电压为9 V时,最大亮度为21 240 cd/m²。当驱动电压从4 V增加到9 V时,色坐标从（0.36,0.38）变化为（0.27,0.29）,均处于白光区域。     

Pressure-induced phase transitions of multiferroic BiFeO3

Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral （R3c） phase of BiFeO3 first transforms to monoclinic （C2/m） phase at 7 GPa, then to orthorhombic （Pnma） phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2θ=7° in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic （Pbam） phase, indicating the coexistance of monoclinic phase with orthorhombic phase in low pressure range.     

天基激光武器系统的发展

介绍了天基激光武器系统的概念、组成、应用和关键技术,分析了激光对目标的杀伤程度,并给出了相应的参考阈值。针对系统的关键问题提出一些解决方法,包括高能激光器的研制和种类,大口径反射镜研制技术和结构形式,以及天基目标捕获跟踪瞄准(ATP)系统精度的影响因素和提高精度的方法。通过对天基激光武器系统发展的研究,为该系统的进一步发展和精度的提高提供研究方向和理论基础。     

一维锰氧化物纳米棒在以O2为氧源的苯甲醇氧化反应中的催化性能

采用水热法合成MnOOH一维纳米线,通过MnOOH在不同气氛和温度中煅烧得到尺寸和形貌相似的不同锰氧化物,并用于以O₂为氧源的苯甲醇液相氧化反应. 结果表明,MnO₂对苯甲醇氧化反应具有较高的催化活性. 通过XPS、SEM、TEM和H₂-TPR等手段对催化剂的形貌和结构进行了表征,并讨论了可能影响反应活性的一些因素. MnO₂的良好催化性能可能与其晶格氧具有较高的迁移率以及氧化还原能力有关. 通过简单的焙烧处理,可以使MnO₂催化剂在苯甲醇氧化反应中具有良好的重复使用性.     

Local hydrated structure of an Fe2+/Fe3+ aqueous solution: an investigation using a combination of molecular dynamics and X-ray absorption fine structure methods

The hydrated shell of both Fe2+ and Fe3+ aqueous solutions are investigated by using the molecular dynamics (MD) and X-ray absorption structure (XAS) methods. The MD simulations show that the first hydrated shells of both Fe2+ and Fe3+ are characterized by a regular octahedron with an Fe-O distance of 2.08 for Fe2+ and 1.96 for Fe3+, and rule out the occurrence of a Jahn-Teller distortion in the hydrated shell of an Fe2+ aqueous solution. The corresponding X-ray absorption near edge fine structure (XANES) calculation successfully reproduces all features in the XANES spectra in Fe2+ and Fe3+ aqueous solution. A feature that is located at energy 1 eV higher than the white line (WL) in an Fe3+ aqueous solution may be assigned to the contribution of the charge transfer.